The Generation and Optical Activity of Misfit Dislocations by Very Low Level Transition Metal Contamination of SiGe/Si.

Abstract

ABSTRACTAn initially pseudomorphic Sio.93Geo.07 layer is forced to relax after the deposition of 0.003 monolayers of Cu contamination and a 600°C anneal. Photoluminescence shows the dislocations have similar luminescence features (D1 to D4) to dislocations generated in bulk silicon. TEM is used to study the generation of the misfit dislocations. It is shown that the half loops form at the sample surface and a mechanism that involves the action of both the metal contaminant and the surface steps is suggested to explain the geometric arrangement of the dislocation loops that are present. The sample was found to be only 22% relaxed whereas equilibrium theory predicts 92% relaxation.